Rotary stepping switch



June 1, 1965 w. A. KRoPP 3,187,144

ROTARY STEPPING SWITCH l/ /l/J/ 2 INVENTOR.

JuneA 1, 1965 w. A. KROPP 3,187,144 v ROTARY STEPPING SWITCH i Filed Sept. 14k.- 1964 2 Sheets-Sheet 2 United States Patent C) 3,187,144 norARY STEPPING SWITCH i Willis A. Kropp, Duxbury, Mass., assigner to General Filed Sept. 14, 1964, Ser. No. 396,301 8 Ciaims. (Ei. 29d-105) This is a continuation-impart of my application Serial No. 232,928 led October 25, 1962.

The present invention relates to electrical switch mechanisms and more particularly to a rotary stepping switch.

It is an object of the present invention to provide a rotary stepping switch which is capable of controlling a large number of contacts but which is positive and reliable in its operation. It is a related object to provide a stepping switch which is highly versatile and which may be easily and quickly modified to provide for either sequential orsimultaneous switching of the contacts or various combinations thereof. Thus it is an object to provide a stepping switch having numerous switching possibiiities enabling it to be used in a wide variety of applications and which may be tailored to the application in a few moments time for supplying an oiic-the-shelf item in a warehouse or a supply depot, making it unnecessary to carry a large inventory of switches limited to particular switching or contact arrangements. Indeed, it is possible to modify the switch to accomplish a desired switching function, or to accommodate changes or improvements in the circuit, even when the switch has been already installed as part of a larger electrical apparatus.

, It is another object of the invention to provide a switch which is capable of simultaneously operating a large number of contacts but which is free-acting, having low friction and with no possibility of `wedging or jamming and which may therefore be operated reliably by a low power stepping motor. In this connection, it is an object'to provide a switch which is capable of operating, even without any lubrication, `for long periods of time and with little or no maintenance. It is a more specific object, in one of-its aspects, to provide a switch in which the operating forces are applied to the switch elements by radial camming action and which avoids any necessity for converting the rotary input motion to movement in the axial direction.

It is still another object of the present invention to provide a rotary stepping switch which is highly compact, enabling use, if desired, in miniaturized equipment, and

which provides a convenient array or" output terminals for wiring or' cabling to kassociated circuit elements. In this connection, it is an object to provide a rotary stepping switch which may be inexpensively manufactured and which is inherently simple in both construction and operation.

Other objects and advantages of the invention will become apparent from attached detailed description yand upon reference to the drawingsiin which:

FIGURE 1 is an axial section through a switch mechanism constructed in accordance with the present invention and with certain parts omitted for the sake of clarity.

FIG. 2 is a transverse section showing the ratcheting mechanism with the drive paw1 in home position and taken along the line 2 2 of FIG. 1.

FIG. 3 is an exploded view, in partial sectionjand partially diagrammatic, of the stepping switch shown in FIGS. 1 and 2.

FIG. 4 is a View similar to FIG. 2 but showing the drive paw1 rotated from its home position.

FIGS. 5, 6 and 7 are stop motion views showing actuation of a typical set of contacts as a result of orbital movement or the drive pinion.

While the invention has been described in connection with a preferred embodiment, it will be understood that I do not intend to be limited to the embodiment described, but intend on the contrary, to cover the various alternative and equivalent constructions included within the spirit and scope of the appended claims.

` Turning now to the drawings, there is disclosed in Fl!"- URES 1-3 a rotary stepping switch 1i) having a cylindrical housing 11 mounting a switch mechanism 12 on an indexing drive mechanism 13. Mounted midway along the housing is a ring gear 15 having internal teeth 16. Meshing with the ring gear are a plurality of pinions 2i). The latter are supported on pins 21 which are equally spaced about the periphery of a pinion carrier 22 mounted on a shaft 23 extending centrally through the housing. Upon the rotation of the pinion carrier 22, by means to be described, the pinions are rotated in an orbital path about the central axis of the ring gear. Because of this orbital motion, it is convenient to think of the ring gear as an involuted sun gear, i.e., one which engages the pinions from the outside rather than from the inside. Moreover the pinions, because of their motion, may be aptly referred to as planet pinions and the carrier as the planet pinion carrier.

Arranged adjacent the path of orbital movement of the pinions, I provide switch elements 30 each formed of an outer blade 31 and an inner blade 32 and with all of the switch elements being arranged in a circular locus. The switch elements may be mounted, as shown, by imbedding them in the end wall 35 of the housing, the projecting ends of the switch blades forming convenient soldering lugs for making external electrical connections. For precisely locating each outer switch blade with respect to its companion, the tips of all of the outer blades may rest upon an annular shoulder 36 formed along one side of the ring gear 15 as shown.

In accordance with the present invention, multipointed cams are provided at the ends of each of the pinions 2i), so phased that the points of the cams engage the switch elements in succession as the pinions are indexed forwardly along their pathA of orbital movement. Taking a typical pinion 20 by way of example, it is provided, as shown in FIGS. 5, 6 and 7, with a cam 4) having points 41, 42, 43, 44. I prefer to employ a four-pointed cam but it will be understood by one skilled in the art that my invention is not limited to use with a four-pointed cam and, if desired, cams having two points, three points, iive points, or even six points may be used. The use of a square cam is preferred since this provides relatively well dened high points spaced suiiiciently to provide clearance at the low regions, or liats, between the points. Moreover, while the points 41-44 Aare relatively sharp in the present embodiment, it will be understood that they may, if desired, be slightly rounded.

The manner in which a typical cam 40 acts upon a typical switch element, or set or contacts, is evident in the stop motion views FIGS. 5, 6 and 7. FIG. 5 shows the cam 4@ in a non-actuating position in which a ilat on the cam is presented toward the adjacent switch element. As the pinion 20 is transported to the right along its orbital path, the meshing of the teeth on the pinion and ring gear cause the pinion to be rotated simultaneously in the counterclockwise direction. This causes the irst point 41 on the cam to be swung upwardly into engagement with the underside `of the switch blade 32, causing the contact carried by the blade to move outwardly as shown in FIG. 6. As will be discussed in connection with the driving or indexing mechanism, the pinion and itscam are preferably held or detented in the position shown in FIG. 6 until further movement causes the pinion to be moved on to the position in FIG. 7. As a result of such further movement, the point 41 of the cam 40 is swung downs wardly away from the blade 32 and opening the switch contacts. It will be apparent that as the `pinion undergoes a still further step of movement, beyond the position shown in FIG. 7, the second point 42 will be swung upwardly against the underside of the nextswitch blade to bring the next set of contacts, shown at the right in FIG. 7, into engagement. Such cammin'g of successive switch elements by theV successive points on the cams occurs simultaneously at each of the pinions inthe set. The number of pinion mounting pins 21, which determines the maximum number of pinions, is preferably equal to one-half the number of switch elements, e.g., eight pins for sixteen pairs of switch blades.

In accordance with one of thefeatures of the present invention, means are provided for normally retaining the pinions in operating position, with the retaining means being temporarily releasable for freeing the pinions and enabling selected ones of the pinions to be removed by endwise withdrawal. Thus, I provide a retaining member t) which is :preferably of disc shape and which has a retaining surface 51. To reduce the friction between the pinions and retaining surface, each pinion is preferably provided, at its outer end, with a tipped portion 52 which may be conical in shape.

The outer diameter of the retaining member Si) is preferably tailored to provide an outer `edge 53 which supports the vinner contact blades 32 in a reference circle for engagement by the points on the cam. The inner blades 32 may be inwardly sprung to assure rm seating in 'the reference position and thereby improve the shockpr'oof characteristics. To facilitate assembly the edge of the retaining member 5t) may be chamfered as shown at 54. rl`he end member 35 of the housing, to which the retaining member 5t) is secured, is preferably held in place by a set 'of longitudinally extending screws 55. Removal of these screws permits the end member y35 and the retaining member 50, which is secured to it, to be withdrawn endwise, thus freeing the pinions 2d so that one or more of the pinions may be axially withdrawn as desired to change the programming of the contacts. As a limiting case, where simple sequential closing of th'econtact's is desired, all of the pinions 2t) may be removed except one.

For the purpose of indexing the pinions between their successive contact closing positions, an indexing mechanism 13 of the positive ratcheting type is employed 'driven by a rotary solenoid 60 having an output shaft v61 and leads 62. The rotary solenoid maybe of the type disclosed in Kropp etal. YPatent 3,147,411, which issued on September 1, 1964. It will suiiice to say that the solenoid output shaft 61 occupies a normal y'reference position and is rocked forwardly when ythe input leads 62 are energized. Deenergization of these leads restores a shaft '61 to its starting position. The shaft 61 thus oscillates through the limited range as succeeding pulses Vof current are applied from a suitable D.-C. source.

Turning more specically to the indexing'or ratchet mechanism 13, it includes a driving pawl carrier 79 having a first arm '71, a second arm 72 and central hub .'73 which is pinned to the shaft 61 by a pin 74. Mounted adjacent the 'drive pawl carrier is a ratchet wheel 80 which forms the driven element of the mechanism, having ratchet teeth 81 and :close coupled to the planet pinion carrier 22. At the 'end of the arm '71 `and in overlying relation to the teeth of the ratchet wheel is a drive pawl 35 which is preferably formed of one or more lam'inations of leaf spring material. The direction of rotation of the solenoid 69, upon being energized, is preferably such as to retract the drive pawl 85 `over one or more of .the teeth on the ratchet wheel. A drive spring 86, which is preferably in the form of a simple coil spring of the tension type, is provided for rotating the pawl carrier clockwise, as viewed in FIG. 2, when the solenoid is deenergi'zed. The spring is Vconnected at its fixed end S7 to the frame of the device while the opposite end 88 is anchoredto the outer end of the arm 71 as shown.

In order to hold the ratchet wheel 8u stationary during the time `that the drive pawl is retracted, a keeper pawlV 90 is used having a first or pointed end 91, a second end 92 and a centr-al pivot 93. A spring 96 having a fixed end Y 97 is hooked over a post 98 on the pawl, thus keeping it biased in seated position. For vthe purpose of insuring that the drive l.pawl remains in contact with .the engaged ratchet tooth during the terminal portion of the driving stroke, a crowding abutment, in the form of a pin 100, is provided just outside of the driving pawl as shown in FIG. 2. The tip of the driving pawl is thus crowded into seated position and overtravel of the ratchet wheel at the end of the driving stroke is prevented.

The operation of the indexing or ratchet mechanism will be apparent upon comparing FIGS.V 2 and 4. As shown in FIG. 2, the rotary lsolenoid is deenergized and the drive pawl carrier is biased into its starting or home position by the driving spring 86. When the solenoid is energized, rocking the pawl carrier counterclockwise, the drive pawl 85 clicks idly over the teeth of the ratchet wheel. In so doing, it takes one or more teeth, the number of teeth being determined by the permitted stroke of the pawl carrier which in turn is determined by astop interposed in the path of the pawl carrier movement. The arm 72 of the pawl carrier may, as shown in FIG. 3, be offset into the plane of the keeper pawl 9@ lso that it bottoms on the end of the keeper pawl to form a stop. Retrograde movement of the ratchet wheel Stiduring the time that the drive pawl is taking a tooth is lprevented by the keeper pawl. An overhanging tab 72a on the pawl carrier overlaps the keeper pawl at the end of the solenoid stroke as shown in FIG. 4 in .order to insure that the keeper pawl is seated in its blocking position.

When the rotary solenoid is deenergized upon termination of the pulse of current, the pawl carrier 70 is free to rotate clockwise under the urging of the driving spring 86. This indexes the ratchet wheel and the associated planet pinion carrier, causing the pinions `to rotate the associated cams as has previously been discussed in connection with FIGS. 5-7. This restores the pawl carrier 70 to the home position shown ih FIG. 2 in readiness for an ensuing pulse of current applied to the solenoid. Since the forward advancement of the pinion carrier occurs upon deenergization of the solenoid, it is dependent solely upon the force developed in the`driving spring 86 which remains constant regardless of the variations which may occur in the voltage applied to the solenoid input leads.

It will be apparent that the foregoing construction provides a rotary switch of the stepping type which is highly versatile as Well as positive and reliable in operation. By varying the number of pinions in the Yassembly and the connections which are made to the rearwardly projecting connection lugs, a wide variety of switch programming can be obtained, limited only bythe ingenuity of the user. Since the switch is so versatile, and since changing the number of pinions takes but a few moments, switches of the present design may be modified at the point of supply in accordance with the orders received so that a single switch may take the placev of a large inventory of more `specialized switches. The construction described above is inherently shockproof since neither shock nor vibration can vaffect the indexing movement and since the switch blades are positively positioned and preloaded in open position until intentionally engaged by the point vof an actuating cam. Since the path of movement of the cam points is epicyclic, the orbital movement of the vpinions is translated, with a minimum amount of friction, into a thrust which is directed radially outward in line with the switch contacts. Yet the movement takes .place so progressively that there is no point, in the switch cycle, where a sudden load is imposed upon the driving mechanism. Stated in other words, positive closure may be achieved even with all of the 'pinions working simultaneously, using a rotary solenoid of limited drive torque capability. A portion of the energy stored in the switch blades is, indeed, usefully returned since the switch blades 32, incident to restoration, urge the cams overcenter. In the event of any overtravel occurring at the points of the cams, the outer switch blades simply lift off of the shoulder 36 to accommodate the overtravel.

The arrangement is to be distinguished from prior arrangements in which rotational movement of an input shaft is converted to axial movement of a series of operating plungers and where binding or jamming of the mechanism may occur. It is found that the present mechanism, by contrast, is capable of functioning even without lubrication over many thousands of switching cycles.

The switch is inherently compact, with the internal space being efficiently utilized so that the switch can be integrated with other electrical equipment made of miniaturized components.

While the invention has been described in connection with a cam of square configuration, it will be understood that any symmetrically formed cam or star wheel having spaced projections may be used; indeed, the term cam may be aptly applied to an extension of the pinion teeth where such teeth are caused to act upon the switch blades directly. The term shaft, as used in the following claims denotes any rotating element for advancing the pinions. The term indexing drive refers to any advancing means for stepping the shaft forwardly by equal increments. The term ring gear will be understood to apply to any gear capable of meshing with the pinions to provide the orbital pinion movement, whether engaging the pinions from the outside or from the inside. Moreover, the term orbital refers to the bodily movement of the pinions and one skilled in the art will appreciate that it is not necessary for the pinion axes to be parallel to the central shaft for the advantages of the invention to be secured. Also, while the switching elements, or blades, are arranged in a cylindrical locus in the preferred embodiment, all that is necessary is that the switching elements be arranged in a circle and the particular orientation of the blades will depend, in part, upon the orientation of the pinion axes. Thus, where the pinion axes are radially arranged, as in the parent application, the switch blades may be radial rather than axial.

I claim as my invention:

1. In a stepping switch the combination comprising a cylindrical housing, a shaft extending centrally therein, a ring gear, a planet pinion carrier mounted on said shaft and supporting a plurality of pinions equally spaced from one another in mesh with said ring gear, a plurality of switch elements arranged in a circular locus adjacent the path of movement of the pinions, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith for engaging the switch elements in succession, and an indexing drive mechanism coupled to the planet pinion carrier for indexing the same so that the points of the cams are brought successively into engagement with successive ones of the switch elements.

2. In a stepping switch the combination comprising a ring gear, a plurality of planet pinions spaced about the ring gear and in mesh therewith, means including a drivel shaft for rotating the planet pinions in an orbital path about the axis of the ring gear, means for indexing the shaft, a plurality of switch elements arranged in a circular locus adjacent the path of movement of the pinions, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith for actuating the switch elements in succession as the pinions are orbited by the indexing movement.

3. In a stepping switch the combination comprising a ring gear, a plurality of planet pinions spaced about the ring gear and in mesh therewith, means including a drive shaft for rotating the planet pinions in an orbital path about the axis of the ring gear, a plurality of switch elements arranged in a circular locus adjacent the path of Y operating position thereby to modify movement of the pinions, each of said pinions having a multi-pointed cam drivngly connected to the pinion and coaxial therewith for actuating the switch elements in succession as the pinions are orbited, retaining means for normally retaining the pinions in operating position, said retaining means being releasable for enabling selected ones of the pinions to be removed by withdrawal endwise out of operating position.

4. In a stepping switch the combination comprising a ring gear, a plurality of planet pinions spaced about the ring gear and in mesh therewith, means including a drive shaft for rotating the planet pinions in an orbital path about the axis of the ring gear, a plurality of -switch elements arranged in a circular locus adjacent the path of movement of the pinions, a shaft indexing means for causing the pinions to advance step by step, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith, said cam being so phased that the points thereon are presented successively to the switch elements as the pinions are orbited by the indexing movement.

5. In a stepping switch the combination comprising a ring gear, a plurality of planet pinions spaced about the ring gear and in mesh therewith, means including a drive shaft for rotating the planet pinions in an orbital path about the axis of the ring gear, a plurality of switch elements arranged in a circular locus adjacent the path of movement of the pinions, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith, ratchet means for indexing the shaft between successive positions, the cams on said pinions being oriented so that the points of the cams are presented in succession to the switch elements as the shaft is advanced between its successive positions.

6. In a stepping switch the combination comprising a housing, a drive shaft centered in the housing, a rotary solenoid at one end of the housing, a ratchet mechanism interposed between the solenoid and the drive shaft so that the latter is indexed incrementally upon successive energizations of the solenoid, a ring gear in said housing, a plurality of planet pinions spaced about the ring gear and in mesh therewith so that the pinions undergo orbital rotary movement step by step as the shaft is indexed, a plurality of switch :elements arranged in a circular locus adjacent the path of movement of the pinions, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith said switch elements being so spaced that they are engaged in succession by the points of a cam as a result of the successive energizations of the solenoid.

7. In a stepping switch the combination comprising a cylindrical housing, a shaft extending centrally therein, a ring gear, a planet pinion carrier mounted on said shaft and supporting a plurality of pinions equally spaced from one another in mesh with said ring gear, a plurality of switch elements arranged in a circular locus adjacent the path of movement of the pinions, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith for engaging the switch elements in succession, and an indexing drive mechanism coupled to the planet pinion carrier for indexing the same so that the points of the cams are brought successively into engagement with successive ones of the switch elements, said housing including an abutting surface for engaging the ends of the pinions for maintaining them in operating position and having provision for temporary removal of the abutting surface for permitting endwise withdrawal of selected pinions from the program of operation of the switch elements.

8. In a stepping switch the combination comprising a cylindrical housing, a shaft extending centrally therein, a ring gear, a planet pinion carrier mounted on said shaft and supporting a plurality of pinions equally spaced from one another in mesh with said ring gear, a plurality of switch elements arranged in a circular locus adjacent the path of movement of the pinions, each of said pinions having a multi-pointed cam drivingly connected to the pinion and coaxial therewith for engaging the switch elements in succession, and an indexing drive mechanism coupled to the planet pinion carrier for inldexing the same so that the points of the cams are brought successively into engagement with 'successive ones of the switch elements, a ratchet mechanism includcarrier, said ratchet mechanism having a 'rotary solenoid for progressively indexing the ratchet Wheel upon successive actuations of the Solenoid.

References Cited bythe Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary xwmz'ner.

ROBERT K, SCHAEFER, Examiner. 

2. IN A STEPPING SWITCH THE COMBINATION COMPRISING A RING GEAR, A PLURALITY OF PLANET PINIONS SPACED ABOUT THE RING GEAR AND IN MESH THEREWITH, MEANS INCLUDING A DRIVE SHAFT FOR ROTATING THE PLANET PINIONS IN AN ORBITAL PATH ABOUT THE AXIS OF THE RING GEAR, MEANS FOR INDEXING THE DRIVE SHAFT, A PLURALITY OF SWITCH ELEMENTS ARRANGED IN A CIRCULAR LOCUS ADJACENT THE PATH OF MOVEMENT OF THE PINIONS, EACH OF SAID PINIONS HAVING A MULTI-POINTED CAM DRIVINGLY CONNECTED TO THE PINION AND COAXIAL THEREWITH FOR ACTUATING THE SWITCH ELEMENTS IN SUCCESSION AS THE PINIONS ARE ORBITED BY THE INDEXING MOVEMENT. 